This invention relates to a carbon black pelleter. In particular, it relates to a carbon black pelleter of the type having a shell and a rotating shaft with pins radially mounted thereon.
Carbon black produced in commercial operations is usually in the form of finely divided solid particles which, in order to facilitate its handling, transportation and to increase its bulk density, must be pelletized. The particles of finely divided carbon black and a pelletizing agent, such as water or hydrocarbon liquid, are introduced into a pelleter which usually includes a horizontal elongated cylindrical chamber and a shaft extending therethrough. The shaft has radially mounted thereon pins which project radially outward and closely fit inside the chamber. The pins are usually arranged in a plurality of rows, each row forming a helical pattern around the shaft.
Generally, a wetting agent and carbon black are introduced at one end of the cylindrical chamber and as the shaft is rotated the pins coming in contact with wetted carbon black particles apply the necessary agglomerating forces to form pellets. The pelleted carbon black is withdrawn at the other end of the pelleter chamber. The details of the operation of a conventional carbon black pelleter are well known in the art as disclosed, for example, in U.S. Pat. No. 2,306,698; U.S. Pat. No. 2,861,294; U.S. Pat. No. 3,825,233; and U.S. Pat. No. 3,579,717, which are incorporated herein by reference.
In such conventional operation carbon black accumulates in between the paths traveled by the outer ends of the pins. This necessitates intermittent cake removal and causes non-uniform size product as some of the cake dislodges between clean-ups and is carried out of the chamber with the product.
The present invention obviates some of the problems encountered in the prior art.
Thus, one object of the invention is to provide an improved method for pelletizing finely divided carbon black.
Another object of the invention is to make the pelletizing of finely divided carbon black more efficient by eliminating the interruptions and expenses caused by the periodic removal of carbon black cake formed on the inner wall of the pelleter chamber, or, in continuous pelleting operations, minimizing the effect of cake buildup being dislodged and exiting with the properly formed pellet.
Still another object of the invention is to provide a process which produces pellets having uniform, or at least narrow range, particle size and which does not contain substantially any large, irregularly shaped carbon black agglomerates.
A still further object of the invention is to eliminate or at least minimize the deposits of carbon black cake on the inner walls of the pelleter chamber.
Still another object of the invention is to make the operation of pelleting carbon black more efficient by eliminating the step of removing from the final product carbon black of irregular size carbon black cake formed as the result of dislodging of carbon black cake from the pelleter walls.
Other objects of the invention will become apparent to those skilled in the art upon studying this disclosure.